


Pulling Favors

by BEWD4133



Category: Yu-Gi-Oh! - All Media Types, Yu-Gi-Oh! Duel Monsters (Anime & Manga)
Genre: Explicit Sexual Content, F/M, Friends With Benefits, Horny Teenagers, Large Cock, Oral Sex, Plot What Plot/Porn Without Plot, Puberty, Sex for Favors, Teenagers, Vaginal Sex
Language: English
Status: Completed
Published: 2019-07-08
Updated: 2019-07-08
Packaged: 2020-06-24 18:18:28
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 6,987
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/19729144
Author URL: https://archiveofourown.org/users/BEWD4133/pseuds/BEWD4133
Summary: Rebecca has gotten used to exchanging favors with Mokuba Kaiba, but, as they both near the end of puberty, it was only a matter of time that she finds herself asked to do more than she bargained for.





	Pulling Favors

**Author's Note:**

> Over a decade ago, it was a Mokuba/Rebecca fic on AFF that help spark my interest in writing, so after all this time I decided to do one of my own.

In an office at the heart of Domino City, a buzzer goes off at the door to which the occupant awaits in a luxurious executive chair. As the younger brother to the CEO of KaibaCorp, Mokuba had gained his own expanded role and influence over the years, now a few months past his seventeenth birthday. His attire was a pressed and proper white business suit although his hair remained as long and unruly as ever. Upon giving his approval to open the door, a female close to his age dressed in the attire of an elite college student with a coat, tie, and skirt stepped into the room.

"Rebecca," the young businessman greeted his visitor, "It's nice to see you again."

"Save the small talk," she found herself a seat.

"Not even a hello?

"What's the need? You already know why I'm here."

The one who had come for the younger Kaiba brother was the young, dueling academic Rebecca Hopkins. Only months older than him, the blond-haired girl with the reading glasses had still done quite well for herself, getting accepted into a highly prestigious university. Her tracking life had already been largely laid out for her, but her business today concerned a different person entirely.

"Your gramps needs a little extra bit of funding for his next research project?"

"He's as ambitious as ever. Too ambitious for his age according to the people he usually gets to provide the funding," Rebecca spoke of her grandfather, Professor Arthur Hopkins.

"And you're not even going to try debating our usual terms?"

"Why bother? I'm used to it by now. Yugi's still fixated on Anzu. I've got no chance with him right now. No harm in getting you off one more time. Better someone high up at a powerful company than a potential college dropout. Just a bit more practice for if I ever do get my turn."

"If that's how you honestly feel then I have no reason to stop you," Mokuba spun his chair around, "In fact, I won't even request anything special. Just do what comes to mind as long as it works."

"What works, huh?" her mind thought it over but quickly settled on a blowjob for the Kaiba. How else could she have expected to get a wealthy teenager to throw his influence for her? Despite what it might look like to an outside observer, she didn't consider them to be a couple, but it wasn't quite sexual harassment to her either. Rebecca would've called them friends with benefits for lack of a better phrase. Mokuba used his Kaiba Corp connections to pull favors for her and others and he would do get these sorts of favors in return. She could've easily turned him down in disgust their first time together, but Mokuba did enough to keep her entertained in the process to have her willing to come back, and he proved to possess some admirable assets of his own for her to make use of.

"My, aren't you oddly generous today?" Rebecca pulled her chair up across from him, still a tad too proud to casually get on her knees.

"I've been rethinking some stuff lately," he reflected, "It's no fun if the girl isn't into it at least a little."

"Is that why you started doing that?" she pointed down.

"Doing what?" he blinked.

"Stuffing a little something extra in those dress pants," Rebecca noted the outline on his groin, always present but now obvious in a way that it would be spotted even by those who were not deliberately looking for it, "It's a simple way to get people a little interested in you before you even propose doing anything with them."

"What makes you think that?" he cocked an eyebrow.

"As a repeat... customer, I'm aware that what you have there is impressive, but it's never come with a bulge quite that nice."

"Is that so?" Mokuba sensed the emerging opportunity.

"Y-Yes," Rebecca caught some worrying vibes emanating from his creeping grin.

"Then you should hurry up and get started if you know me so well. This should be over in no time."

"If that's how you're going to be, then no objections her," Rebecca stretched her fingers and readied them for action.

Waiting patiently for just the right moment, Mokuba watched Rebecca pull herself forward to get in easier distance of him for her arms. He spread his legs apart to lure in his prey, and once he made the move to reach for his zipper, he released just enough of his libido to cause his bulge to make a noticeable jump just before she could make contact. The girl was too astute for the message to be lost on her as she stopped in her tracks.

"What's wrong?" he now a fully devious smile during her momentary pause

"...So, you're for real then," she flatly cut to the chase.

"As real as I've ever been."

"Even I have to see this," she promptly recollected herself and finished her grab at his zipper.

Both parties reveled in what had almost become a mundane process for them. Rebecca took her sweet time fishing out and freeing his manhood, probing his drawers from anything less the genuine and testing out a few other theories lurking in her head. Her facial expressions as she went through the motions were all the entertainment that Mokuba needed until she finally tugged his meaty member out from his pants fly. She was too professional to give off any outward expressions of shock but Mokuba could interpret what her muted reactions really represented within her brain.

"All of this and barely even hard," his squishy appendage still provided more than a fistful for her to hold where a single hand used to be enough, "I thought maybe you had already popped a boner but..."

"You have to work a bit more than before for that," he declared.

"I don't think it'll take that much but okay," Rebecca was pleased with how his ascension had already gotten started.

Even if he really had grown since their last meeting, she knew she could still hold her ground by finishing him off as quickly as possible. Using a hand to support the base left another half to work on which she didn't hesitate to pop into her lips. She took his expansion in her mouth accelerating to a greater rate than she had ever experienced as a positive sign at the least. He hummed in delight from her but never lost the smirk that she took as a personal statement of dominance. Instead, it was the grin on her face that was wiped off quite literally as his girth swelled against her jaw to a degree that she had never practiced for. She stubbornly tried to force her way through it but the pressure forced her to pull herself off of his dick before her jaw dislocated altogether. Mokuba was a tad irritated by the slight scraping his dick got from her teeth but the taste of victory more than made up for it.

"Hey, no biting," Mokuba playfully scolded her while she tried to regain her breath.

"Keep that up and I'll bite it clean off," she remained defiant until she got her first unobstructed view of just what it was she was trying to force her mouth around.

"Too bad. You stopped just short of getting me fully hard," he taunted her as her true surprise finally became too much to properly suppress.

"Bullshit, how is that not a full erection by now?" she weakly objected but was swiftly rebuffed by Mokuba taking the final step to reach his fully aroused state right before her eyes, fueled by his excitement at her helplessness and invoking images in her mind of the mightiest men she had looked up online, "How is that even possible?..."

"The last time we did business together was just before I turned seventeen," Mokuba spread his legs fully and removed his pants entirely to give his loins the space they now warranted, "Nature decided to give me a healthy growth spurt as a present, an extra inch in every direction."

Thanks to her intellectual curiosity, Rebecca knew from previous measurements how significant of a statement that was. At sixteen, he had already exceeded what she knew to be the adult male averages by a full inch, but to add another inch on top of that would leave here with something that she could only find on very specific sites with very specific search terms. Still, what she saw only demonstrated his claims to be the absolute truth and left her with but one final recourse to assess her current position. Shuffling through her pocket, she fetched the lone condom she had brought to be used for the day's activities, previously confident it would be all she needed. Now though, she could only meekly tear it open confirm what she feared, and he knew was inevitable. The thin material stretched to its limit just to get over the head and began to show signs of tearing by the time she had rolled it a third of the way down his shaft.

"Damn it," she gave up before even getting halfway down, "That's the largest size they sell at the Pharmacy."

"Nope, I'm special order only now," he boasted by using his rigid mass to shred the rubber entirely.

"And what do you expect me to do with that... monster," she bit her lip with frustration masking a new sense of arousal.

"I don't expect you to do anything. You're the one who's here for money," he replied, "I told you to satisfy me and gave you the freedom to choose how to do so including with or without a condom. Since you couldn't be bothered to bring one that could fit me I guess you plan to do it without."

"That's not fair. You could've just as easily ordered some!"

"I was too busy shopping for new underwear to better accommodate that bulge you so rudely pointed out."

"Fine, just let me go get some better condoms and we can finish up next time."

"Next time?" he incredulously flexed his burgeoning manhood, "I have a boner now! You think it's easy having a hard-on while hung like this? If you blue-ball me then you can just forget the whole thing."

"Cut me a break here, Mokuba. What am I supposed to do?" his goading wore her down, "I can't... you're... I mean it's too..."

"Too what?" he leaned in an ear

"It's... it's too much... you're too big!" she gave up at last "I'm not ready to deal with that. I'm not one of the floozies who comes in every other week looking for a promotion. I just came to help my grandfather. I never even thought to prepare myself for a cock like that. I'm finished here."

"Hey, don't say that," Mokuba consoled her now that he had gotten the forfeit he craved, "Lately, I've had girls not even will to try getting their mouth on me. The effort you gave is admirable in its own way."

"But that's all I have it in me to give."

"I never said we couldn't be gentle. That's just what you assumed you had to do. Just because I have a porn star dick doesn't mean we have to do it rough like one."

"I don't know what else I can try to do."

"Just start easy and only go as far as you think you can."

"Will that really be enough?"

"Here, I'll show you," the Kaiba reached out for her hand.

Taking her wrist, Mokuba guided her hand back to his shaft that was as solid as ever. He surprised her with how he shuddered at the contact, but even more with how he carefully and slowly led her hand up and around his length. No longer consumed with the need to prove herself and finish him off, she could appreciate all the other ways it had matured from before.

"It's surprising that it can stay so hard while so big," she murmured.

"Sometimes it is a challenge, but that's how much you've turned me on here," he released her hand to continue moving independently.

"Really, this much? I didn't think I was your type. I just got good at using my tongue."

"I get all sorts these days, but you have an appeal that goes beyond a nice pair of tits."

"Like what?"

"You're so much feistier than the others, much more curious."

"Curious how, exactly?"

"Plenty of girls will simply grab my dick, but I can tell you're studying it even now with how you move your fingers."

Mokuba stopped talking so that she could refocus on what she had continued to knead almost subconscious in her palm. Rebecca remained at a loss for what to say, think, or do, but that only amplified the tension between them as Mokuba's excitement skyrocketed through the gradual breaking of her prim and proper facade. The entire situation was unlike anything she had ever imagined in her life, yet nowhere in her did she feel truly bothered by it. Her demeanor was primarily one of patience and even some curiosity as he said. While she had been trying to take the lead before, Rebecca was content to now go with the flow to feel out where it was going to lead. The composure she now demonstrated while working her hand along his shaft put Mokuba in position to now be the one impressed with her. Even as the boy himself believed he was as hard as he could get, he could feel himself somehow continuing to expand, lengthen, and widen, and Rebecca could certainly see how he stretched further out towards her.

"Unbelievable, you're still getting bigger..." she clearly observed.

"So how's that for a white dragon?" he growled.

"How much larger can you get?

"Don't know. I'm still working my way through the end of puberty. You curious?" he teased.

"Maybe a bit," she couldn't help but admit.

"To be honest, you're the first person to have me feeling quite like this. It's so hard it almost hurts, yet I'm so fired up, that I don't want it to stop."

"What do you mean?" she embraced her dirty curiosity more openly.

"I love the stern way you're staring at it right now," Mokuba looked into her eyes through her glasses while they remained trained on his dick, "Even after all that trouble, you somehow really do want to see me get bigger, and it makes me want show you how much more I still can grow."

"It's certainly a sight to behold," Rebecca smiled at how his shaft rose just a bit more through her fingers, "But dare I say that even the single extra inch you mentioned before is an outdated figure?"

"Perhaps even I underestimated my full growth spurt," he confessed with another slight swell in girth, "How about you help me track my recent growth?"

Rebecca nodded more confidently than before and started to knead his member in ways aimed at drawing out any latent energy dwelling within. Making full strokes from head to base had it get a little longer with each completed motion. Kneading the softer areas would bring about a thickening that would pry back at her fingers. It took so much out of his racing heart to support it that Mokuba wondered if he'd end up passing out, but at that point Rebecca had settled herself in enough to work up the nerve to stick out her lips and plant a kiss squarely on the glans. This prompted all that he had left of his adolescence to come rushing out all at once to bolster his manhood to a dimension on par with the very best he had ever checked out on an adult video. He could only hope their still youthful bodies would be able to handle it.

"I would've brought my ruler if I had known this would happen, but even from here I can safely say that it's certainly no less then eight and a half inches long and six and a half around now," she analyzed him with a tilt of her glasses, "A dick worthy of internet."

"Aw man," he was now the one left stunned, "Guys in my position typically have to pay up for sex, but I might be at the point where people would pay me for a go at this dick."

"Now, I think It's more than safe to say that my hands won't be enough.".

"Yeah, I know it's a lot to ask you to take all the way but would you at least put your lips around the top," he was surprisingly considerate.

"Alright," she licked her lips and went in on him much more well prepared then before.

What she struggled with earlier was out of the question now but she was still able to do what was absolutely necessary and get the glands along with the upper portion of the shaft into her mouth for her to run her tongue along the underside. The spike in sensitivity that accompany this level of arousal his made immediately apparent like how even a basic look could elicit a shutter from him. The flavor obtained a fresh zest that she had never spotted before or at the very least never properly appreciated. The movements of her tongue that were designed to hit him where he would feel blessed we're now aimed at sampling and savoring the new taste in greater detail. She soon wound up taking the head out of her mouth so that she could run her tongue along the entirety of his member.

"Oh fuck, Rebecca," he shuddered as she went at him like an ice cream cone, "When did you find it in you to do it like that?"

"If I'm the only one who can make you this big then I have to be the one to see what you can really do, when you're," she squeezed the top and licked the bottom, "You did say I was the only one, right?"

"Yeah," he somehow still felt the urge to grow even more excited and hardened in her grip to a nigh impervious degree, " I couldn't even deal with this on my own anymore. Please don't think about stopping."

"As long as you keep thinking about that money for my grandfather you can finish wherever and however you like," she offered, taking sometime to massage his balls that had gone neglected before now.

The rush of energy emanating from his burgeoning manhood combining together with their natural youthful exuberance forced Mokuba to fall all the way back in his chair. His neck and back arch as his head turned upward to release a groan into the air. Rebecca lifted her head to place his glands into her lips once more with both hands tenderizing is much of his meat they could. By now, she had already had some of his pre-cum leak onto her face and hair, and now had it pooling on her tongue. Now she was handling him more like an ice pop, working hard to squeeze out his succulent juice. Working up the courage to go from a third to a half of him wound up being the final ingredient she needed to trigger his eruption which had increased in virility and volume in direct proportion to his member before. The spurts she was accustomed to now came out in full-on streams far too turbulent for her to take in her mouth. She pulled off before her mouth could overflow completely but pump came all the way through as his excessive release leapt out the into the air and rains down on her from above, making its way all over her hair, face, and clothing. It was a climax that both would remember unlike any before it.

"How's that, Mokuba?" Rebecca was just as amazed with him for what he just did as she was with herself for causing it.

"Money can't buy something like that," he sat up, still short of breath.

"But it can buy my grandfather's research which I assume will now be funded," she reminded him.

"Of course, of course," he gradually composed himself until taking a good look at the girl before him coated in his essence, "Oh, wow..."

"What?"

"You might be the sexiest thing I've ever seen right now. My cum really got all over."

"Ah shit," Rebecca never realized just how extensively he had coated her with his seed, "Even my glasses."

Seeing her delicately pull out a cloth to wipe his splooge from her lenses was the final straw for him. All of his arousal that had dissipated in his release came flooding right back. His manhood shot back to life as if nothing in the last few minutes that even happened at all only now with an even more urgent need coursing through it.

"Rebecca..." Mokuba sighed just loud enough for her to hear.

"Yeah?" she turned back to him only to get a startled when she spotted his member standing as tall as ever.

"I need you," he took another deep breath.

"I can see that..." she laughed awkwardly at his erection, "But I already held up my end of the deal."

"I know but that was just a favor because you needed me. This time I need you," he emphasized to which she understood but was unsure of how to proceed.

"What? So I need to do that all again?"

"No, that won't be enough. After seeing what I did on the outside, I need to see what I can do on the inside."

"You mean... you want to be in me?"

"We did it once."

"Briefly, with a condom, and a lot less meat on you like that."

"Please?"

"I don't know if I can. I can't conceive that I would be able to after all it took just to do it with my hands and mouth."

"But you still want to at least try and see if you can do it? Right?"

She couldn't deny that the challenge was an enticing one. If could take that then what would there be that she couldn't take? What would it feel like to be spread open that far and reached into that deeply? All of a sudden, the seat in his lap was starting to look more and more comfortable. Before she realized it, her own juices were trickling out of her skirt and onto her thigh, causing Mokuba's erection to twitch in delight when he noticed it as well.

"I get to be on top though," she set her final terms, "I won't be having you tear me in two with that thing.

"No problem, do it however you like," he accepted.

Removing her panties from underneath her skirt was the only last bit of preparing that she needed to do. No other part of her body mattered to her, compared with the daunting task of taking his beast into her womanhood. She stood from her chair and moved to where she was facing him with his member pointing right up into her, placing her hands on his shoulders for her final bit of mental preparation.

"Damn, I can't believe I'm doing this," she muttered before finally letting her hips begin to drop.

Her hand reached down to hold Mokuba's member upright and he watched with wonder as she brought it up to her the moist lips of her pussy. By no means was it their first time, but it might as well have been with how much stretching it took just to get the head in. Getting the first few inches of his swollen, rock-hard, and substantial shaft in created the image in her mind of a large cucumber penetrating her womanhood.

"Oh God, I really can't believe I'm doing this," Rebecca's voice went up an octave once she got past the quarter mark of his manhood.

"Take it easy. You're doing fine," Mokuba encouraged her while mesmerized by the way his member pried open her vagina inch by inch.

"Mmmm, so fucking big, so fucking big..." she bit her lip and repeated while she continued her way downwards once she took in the first half.

Her body almost did finally give out when she got to the last two inches, but Mokuba's surprisingly thoughtful arms reached around her to support her for the final stretch as she fully planted herself onto his rod and into his lap. Even after amazingly taking in all he had, the feeling of such a behemoth making itself at home within her took a good deal of time and several deep breaths for her to accustom herself to. The new sensation of his flesh being directly bonded with hers was a lot for Mokuba's mind to adjust to as well.

"Oh... shit... Mokuba... It... It's like..." she eked out between pants.

"Yeah, it's something else," he kept his hands firmly on her back but pulled her a little bit closer.

"It's... It's... Ooooooh" one single tremendous shudder rushing through her body seemed to refresh her ability to speak in complete sentences, "It's almost beyond belief..."

"Yeah, I didn't think it'd be like this either," he agreed with a glance into her eyes.

"It's just so... gargantuan," she spoke more closely into his ear, "I never fathomed that I would ever have this much cock in me all at once."

"And I never imagined you would take it all at once," he gently laughed back at her.

"Oh Mokuba, I don't even know what to think right now," she grabbed onto him as he maintained his hold on her, "It's stretching apart my womanhood so thoroughly that my entire body feels like it's being filled by it. Every inch feels so monstrous, aching to tear me apart completely, and yet, somehow, it actually feels kind of nice."

"Really?"

"It's crazy, I know, but there's something oddly fulfilling about giving all I have to this mammoth member of yours. It hurt a bit at first, but after a certain point it simply overcame me just what an amazing thing this is to have in me."

"Well, you have me feeling nice too. I mean, it's been a while.

"Six months since we've seen each other," Rebecca recalled

"Yeah but not just that. I was thinking that it's also been a long time since I felt like I had enough room down there," Mokuba clarified.

"Oh?"

"It's not easy. I mean it's fun to gloat about, but my pants have only been feeling more and more restrictive and I always end up forcing so much with the other girls now. This is the first time since this sudden growth spurt kicked in that I really feel comfortable, you know, like I have enough space to just... let it out," he confessed.

"Ooooh," she felt herself become even more at ease with him, "Well, it's so rigid that it's kind of just doing what it wants in there, but that hardness feels really good too."

"and your pussy is super soft, warm, and mushy. Slipping into it feels so natural for me," he even started to blush, "It's great. Thanks, Rebecca."

Even as deeply connected as they were, for some reason a kiss still felt awkward for such an informal relationship, but both found a hug more than appropriate for the moment. The intimate exchange of thoughts inspired Rebecca to make her first motions since reaching the base of his shaft. They were only light rocks of her hips but each tiny plunge onto his manhood offer a more electrifying spark than the one before. Its shape was more deeply ingrained in her mind each time his head brushed against her cervix with her awareness of his more minute features increasing in clarity aided by the slick coating of her juices tenderly applied along his length by the lips of her furtherly aroused vagina. His hands seemed to make their way lower down her back in proportion to the rising heat between them. So much so that she undid and discarded the coat she had been wearing over her shirt.

Oh fuck, you're really taking the whole thing," Mokuba let out a gasp, "I've never had it being squeezed all at once like this before."

"You certainly aren't making it easy for me," she huffed, "Always wearing a rubber thoroughly failed to do justice to this incredible texture. That fat head of yours is scraping me so much that going any faster might make me lose it."

"Then at least met me feel a little more of you," he used his hands resting on her waste to guide her into longer strokes.

Wait, wait, shit!" the sudden change in motion introduced more new sensations into her mind than she was ready to handle at once, "Oh fuck, Mokuba!"

"How's that?" he was now going in and out about a third of the way with his member.

With her mental faculties momentarily disrupted, her body resorted to making its more natural responses to him. Her vaginal walls began tightening on his erection in random, frantic intervals. It appeared to be a way of indicating he was too much for her yet only served to invite her to go even farther. He mustered all of his self-control to keep himself from going any harder before she was ready again, but all of that pent-up desire only made its way straight into his member, solidifying and bloating it into a distinctly erotic new shape for her womanhood to contend with which it did with a fierce climax. The boy paused to experience the waves of orgasm crashing over her, both in how he could see her body quivered all over and he could feel it all coming down on his manhood. It was all a shock like he had never known.

"Did you just... cum?" he murmured to stunned surprise.

"Yeah, I think so," Rebecca had slumped back but pulled herself back up with the help of his shoulders

"Wow, that's actually a bit of a first for me, having a girl cum right on my dick."

"Hm?" still re-gathering her strength.

"I've always been too much for them before I finish, but you really did it."

"Uh-huh, I guess I did," she confirmed.

"You're pretty amazing, Rebecca," he gave her a refreshed grin. His erection suddenly had a new sense of pride emanating from it that had her eyes springing back to life.

"Damn, how does that body of yours have a heart strong enough to keep such an enormous dick this hard and have it throbbing so much all over? It's like a jackhammer in my belly," Rebecca was taken aback by his renewed and even further enhanced vigor, so much so that she blurted, "How am I ever supposed to go back to my vibrator?!"

"So, I'm better than a vibrator?" Mokuba seized on her gaffe

"So much better!" she didn't even attempt to deny it

"Thanks, you're a lot better than any toy too," he cradled her, "I outgrew my fleshlight too, you know. Couldn't even get in halfway before."

"I think I can manage at least that much for you since I came first."

"Sounds like we have a new deal then," he announced.

"Huh?"

"Beyond the usual money, I don't mind letting you have some fun with this cock of mine if you ever happen to be feeling frisky. This pussy of yours will make it more than worth it on my end."

"Well, I guess I probably won't ever be casually finding a subject like this on the street or in a science book," Rebecca noted the outline of his penis within her still extending upwards and past her navel, "I suppose I still have a lot could stand to learn here."

"Then it's a deal?"

"It just might be," she was finally primed to begin moving again.

Rebecca promptly re-assumed her prior pace without his assistance. There was still some visible strain to it with every ounce of excitement from his manhood running through her each time she went up and back down to the base, but she was able to remain smooth and consistent with her motions. Her next challenge came when Mokuba began to add in his own movements. He was past the point where he could keep his hips completely still in his seat and the continued pressure of her vaginal walls bearing down on his erection was soon accompanied by some increasingly ferocious twitching from him.

"It really is like a wild animal," she moaned, "Rampaging against all of my most sensitive areas. Fuck, I love it."

"Because you don't let up even when I'm about to explode. If I made you cum once, I have no qualms about making you cum twice."

"Not until you finally cum."

"Even if it's inside you?"

"It'll be our new contract with each other."

"Seems like a binding agreement to me."

In accordance with her promise just earlier, Rebecca pushed herself to get her hips humping along a solid half of his length, maybe even a bit more. Her canal opened itself to accept a ravaging more intense than ever. Now, the bulbous glans she had become enamored this was alternating strikes against her G-spot and cervix. Each time she bottomed out had a healthy thump to it with his lust testicles brushing against her when he gently bucked his own hips in rhythm with hers. His hands drifted from her waist to her hips to provide a little bit of lateral movement that he was yearning for. Sporadically, he would feeling a tightening around his base they would creep its way up her walls and along his shaft that would conclude with a tense squeeze of his head at the end of her passage. In all, it had been way, way too long since Mokuba could revel in being enveloped like this, and it was an even more spectacular sensation than any he could ever remember.

"Fuck, I never thought it could get like this," he hissed, "Like, It's become so sensitive and the whole entire thing feels like it's on fire and now I..."

"You've got so much meat in those loins now, and for the first time you've got someone willing to properly consume it all at once," she finished for him, "Must be quite the special feeling."

"Yes, it his," he gently tugged her hips down to snugly press her groin against his.

"It's only fair for me to appreciate the opportunity for what it is," she shuddered at being wholly filled once more, "I'd probably have to go into porn for another chance like this. Even if you aren't my Yugi, it'd be a terrible waste to pass up such a go with such a colossal dick."

"I'd hate to lose out on this too. We've got a good thing going here."

"Then for our new arrangement, consider yourself the subject of my own study. From now on, I intend to find out just what a big cock can really do."

"You really want to know?"

"Oh yes, you're not done with puberty yet. I look forward to tracking your future growth and any further developments that come along with it. How many more condoms and different toys will you manage to break. I look forward to keeping a very exact count and sharing my conclusions online."

"Don't think I won't be testing you too then," he gripped her firmly by the waist, "How much of this dick do you think that you will you really be able to take? Think of how your innards feel being stuffed with all of this cock already. What will that do to you when thrusting all the way in and all the way out?"

Seriously considering his proposal sent shivers through her limbs and spine with vaginal undulations all over the dick in question.

"I hope you don't expect to always be on top," Mokuba tried to mask how good her trembling felt.

"Risk is the price of discovery," was her final answer, "Better to be fucked silly than spend my life regretting that I never tried it."

"You better mean that because, oh fuck, am I close to really cumming right inside you," he refocused on the pussy tenderizing his manhood right in front of him."

"Yes, that's where I intend to run my first test. Let's see if your cum can win out over what's supposed to be my safe day," she taunted right to his face, "You're the one with the money to pay for a kid anyway."

Even being faced with the very real prospect of sensory overload. Rebecca accelerated and broadened her thrusts to what she felt was just at the brink of her young body and mind being overwhelmed. She managed to get almost as high as three quarters of his shaft in a single stroke. Her speed bumped up to a level comparable to what he would do with his own hand in masturbation. For varying reasons, they were each aware of the concept of edging and quickly realized from a rapid hardening and sudden thrashing from his member that her controlled pace up until now I'd only been setting up the final result to be more explosive. It was a technique Rebecca would be sure to mentally store away while Mokuba found himself going numb to any signals or sensations beyond his loins. His manhood had grown into so much more than ever before and every square inch of it was overcome by the dazzling sensations of her coiling pussy and his imminent eruption. His testicles were no exception, also churning for the incoming storm at a rate he was not remotely aware they could.

"No exceptions then, you had better not dream of slowing down now," he issued a warning that sounded more like a plea, "I'm about to cum. I'm gonna cum so fucking much! You had better handle it to the last drop!"

"Yes, I will no matter what, in the name of science," her thrusts became increasingly automatic as her mind wanted to give way to raging leviathan within.

"Fuck, you're so fucking sexy, Rebecca! Look at you taking all of that fucking cock and loving every fucking inch. Ah fuck, take my fucking cum too!"

With his neck shooting back and every muscle in his body tensing, Mokuba unleashed his seed in an ultimate burst reminiscent of a chemistry experiment gone horribly wrong or horribly right depending on one's perspective. The entire process of having his raw unfiltered spunk gushing inside her was new to her on its own, but she knew that it was also on another level compared to anything she would have had the chance to try before. The first shot alone was enough to surpass what she would have anticipated under ordinary circumstances but then the second, third, and fourth came out just as vibrantly allowing her to reach her own orgasm to go with the fifth, sixth, and seventh, each accompanied by an ample throb and twitch that felt just as wonderful. He made an admirable final effort with his eight before the ninth and tenth came out as lighter satisfied spurts. Even with her womanhood holding it as much as it could, by his fifth shot he had already made a stain the upholstery of the chair on which he was sitting with the final waves rendering unsuitable for any further business.

"The human body is an undeniable marvel of nature," Rebecca concluded as she observed the results of their exchange on both ends.

"Damn, can't believe I really came that much," Mokuba glanced down to the puddle between them.

"And yet I'm confident I could get even more in the right circumstances," Rebecca boldly claimed.

"At the very least you'll have to wait for another day to try that," Mokuba suddenly got an uneasy feeling about just what it was he had now agreed to, "I think that our work here is finished for the time being."

"My grandpa's research is good to go?" Rebecca had come more perilously close to forgetting than she would have liked.

"Every penny," Mokuba let her off of his lap.

"And you'll be good to go the next time I need your "assistance"?" she double-checked.

"Good, I already have a few ideas brewing," she surprised him by dropping to her knees before him as she otherwise hated to do, "but for now though, mind if I collect a little additional data?"

When she fished her smartphone out of her coat pocket, Mokuba figured out the rest. Even after two orgasms, this girl was too erotic for him to turn down in a mood like this. Mustering any remaining lust in him was enough to pop one, last, hell of a boner with her help. After getting the camera active and ready, and an amorous grin on her face, his dick found a new place to comfortably rest right against her cheek. With his erection towering well above her head as a frame of reference where traces of his earlier release still left all over them, she made sure to catch both of their faces in frame for one incredibly masculine snapshot.

"What do you think?" she brought the picture up to him, "The first of many I hope."

"Of what?"

"How many objects your cock is bigger than. My head should make a nice start."

I hope you don't ever intend to give me a boner without a plan to deal with it," he brought her hand back to his shaft.

"Of course not, Mokuba, of course not."

To be continued?


End file.
